Williams, Basil
Oxford University, 1945
Buku Klasik
Williamson, J.A.
Macmillan, 1965
Buku Teks
Christopher Bayly, editor
acts On File Book, 1989
Buku Referensi
Bremner, G. A.
Oxford University Press, 2016
eBooks
Hall, Walter Phelps
Ginn and Company, 1953
Buku Teks